Rolling mill

ABSTRACT

A rolling mill comprising a bearing block supporting the rolls and adapted to be subjected to reciprocating movement, said bearing block being integrally connected to a mobile mechanism comprising two eccentric masses, turning in opposite direction in synchronism with the reciprocatory displacements of the bearing block.

United States Patent Pierre Peytavln Neuilly-sur-Seine, France Dec. 19, 1968 June 15, 1971 Soclete Anonyme Dite: Vallourec Usines A Tubes De Lorraine Escaut Et Vallourec [72] lnventor [21] Appl. No. [22] Filed [45] Patented [73] Assignee Reunies Paris, France [32] Priority Dec. 20, 1967 [33] France [31] 133,147

[54] ROLLING MILL 7 Claims, 4 Drawing Figs. [52] 11.8. C1 72/208, 72/ l 89 [51] Int.Cl B2lb 17/10 [50] Field of Search 72/208, 209, 189, 214

[56] References Cited UNITED STATES PATENTS 1,810,698 6/1931 Drescher 72/189 2,594,126 4/1952 Coe 72/208 2,939,350 6/1960 Nichols et al. 72/189 3,030,835 4/1962 Krause 72/209 Primary Examiner-Milton S. Mehr Attorney-Holcombe, Wetherill & Briscbois ABSTRACT: A rolling mill comprising a bearing block supporting the rolls and adapted to be subjected to reciprocating movement, said bearing block being integrally connected to a mobile mechanism comprising two eccentric masses, turning in opposite direction in synchronism with the rcciprocatory displacements of the bearing block.

PATENTED JUN} 5 m1 3; 584, 489

SHEET 1 BF 2 r 7% id FIG. 1

FIG. 2

PATENTED JUN] 519m SHEET 2 OF 2 ROLLING MILL The present invention relates to a rolling mill with a forming roll in which the moving masses are counterbalanced dynamically.

It is known that in rolling mills having forming rolls the blank which undergoes the rolling is periodically held between two rolls provided with grooves of decreasing section, which cause a reduction in the section of the blank when the rolls carry out a rolling movement on the blank. The rolls are subjected to alternating rotary movements in such a manner as to roll, during each movement, a part of the blank which is displaced each time by a slight amount relative to the rolls.

In the case of a rolling mill for tubes, to which the present invention relates more particularly but not exclusively, the rolling of the tubular blank takes place by locating in its interior a mandrel of generally conical shape and against which the wall of the blank is compressed.

In rolling mills with a stepped roll of known type, it is normal to support the blank in a stationary position, during each rolling movement, and to subject the bearing block supporting the rolls to a traversing motion in relation to the blank, whereby the rolls effect rolling of the blank. The result is that the rolls, the bearing blocks which support them and all the attached members which are necessary for the drive of the cylinders, must be displaced in a reciprocating movement at a rate much greater than is desirable in order to obtain increased output from the rolling mill.

The question of having to drive a considerable mass in a reciprocating movement at a frequency which may be, for example, 150 to 200 oscillations per minute, raises considerable mechanical problems. For example, it is common to find rolling mills with stepped rolls having mobile units which weigh several tons, even several dozen tons.

In rolling mills of this type which are currently used, total counterbalancing is obtained by connecting the oscillating or reciprocating bearing block to a crankshaft motor provided with a counterweight, by means of one or more crank arms. Counterbalancing devices of this type are insufficient for they only make it possible to obtain an effective counterbalancing for horizontal loads. The result is that rolling mills of this type cannot operate at a high speed.

It has also been proposed to improve counterbalancing of this type by suspending on the crank which drives the reciprocating bearing block, a considerable mass by means of a connecting rod. This additional mass has the advantage of counterbalancing to a certain extent the vertical load, and rolling mills of the latter type enable the manufacturing speed to be increased, but they also have considerable disadvantages due to the necessity for using an additional counterweight, (which increases the weight and consequently the cost price of the machine) and also due to the fact that the counterbalancing ofthe moving masses is not effected exactly.

An object of the present invention is to provide a simple means of obtaining a static and dynamic counterbalancing of all the moving parts in a rolling mill with stepped rolls.

According to the present invention there is provided a rolling mill comprising a bearing block supporting the rolls, and adapted to be subjected to a reciprocating movement, said bearing block being integrally'connected to a mobile mechanism comprising two eccentric masses, turning in opposite direction in synchronism with the reciprocatory displacements ofthe bearing block.

Preferably, the eccentric masses which ensure the counterbalancing are rotated by at least one hydraulic motor, the rotor of which is directly coupled to them.

In a particular embodiment of the invention, as will be described in detail hereinafter, the aforesaid mobile mechanism comprises two identical crankshafts, each provided with eccentric masses which are mounted in the same frame and the rotary movements ofwhich are synchronized by gears of the same diameter provided on at least one of the extremities of the said crankshafts. The crankshafts are each connected to the bearing block of the rolling mill by a connecting rod.

In this embodiment it is an advantage to use the crankshafts of the mobile device for transmitting a reciprocating motion to the bearing block,

In accordance with the invention the eccentric masses of the mobile mechanism are chosen in such a manner as to counterbalance the horizontal inertial developed by the bearing block of the rolling mill.

Due to the characteristic feature, whereby the eccentric masses of the two parts of the mobile mechanism turn in opposite directions, the vertical components of the inertia of these masses are automatically cancelled, which makes it possible to obtain a perfect counterbalancing of all the moving parts of the rolling mill.

The shafts of the cranks which have been described above may be horizontal or vertical according to the desired general arrangement of the rolling mill.

Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which:

FIG. I is a diagrammatic sectional view ofa pair of rolls of a rolling mill with forming rolls for tubes.

FIG. 2 is a diagrammatic side view of the pair of rolls shown in FIG. 1, the tube and its mandrel being cut in the plane of the axis of the rolls,

FIG. 3 is a diagrammatic, perspective view of an embodiment ofa rolling mill according to the invention.

FIG. 4 is a diagrammatic, perspective view of a variation of the counterbalancing device according to FIG. 3.

In FIGS. 1 and 2 there are shown diagrammatically rolls 1 and 2 of the rolling mill which are provided with symmetrical grooves 3 and 4, the section of which varies along the periphery of the roll in such a manner as to effect rolling of a tubular blank 5 which is placed in a conventional manner on a central mandrel 6.

The rolls 1 and 2 are mounted in known manner, in order that their axes undergo a reciprocating motion between the points A and B, while the rolls, rotating about their axes, roll on the tubular blank 5. Between each reciprocating movement, that is between the moment when the axes of the rolls arrive at A and the moment when they leave it, there is imparted to the blank 5 a displacement in the direction of the arrow F in such a manner as to bring about the rolling ofa new section ofthe blank.

In FIG. 1 the arrowsfshow the direction of longitudinal displacement and the direction of rotation of the rolls during the rolling motion.

It can be seen from FIG. 2 how the grooves 3 and 4 effect the rolling of the blank 5 by pressing it against the mandrel 6. In order to obtain a perfectly circular section the blank is subject to periodic rotary movements about its longitudinal axis.

FIG. 3 shows diagrammatically a rolling mill according to the invention. In this figure there are again shown the rolls 1 and 2 mounted in a bearing block 7 which comprises in known manner guide means for reciprocating said bearing block in the direction indicated by the double arrow F,. The bearing block 7 also comprises, in known manner, mechanisms for ensuring the rotational drive of the rolls 1 and 2 as well as the synchronization of the rotation of the rolls with the reciprocating motions of the bearing block.

For reasons of simplicity and clarity in the drawing, these known guiding, control and synchronization means are not shown.

A rod 6a which is provided at one end with the mandrel 6 is held firmly during a rolling operation by two rod supports 8 and 9 which permit the introduction of tubular blanks 5 on to the rod.

Tube holders [0 and II are also shown which are subjected to reciprocating movements as represented by the arrows to effect axial movement of the tubular blank 5. These tube holders 10 and II also have, in known manner, means for enabling the tubular blank 5 to be successively rotated as mentioned previously.

There can also be seen in FIG. 3 a mobile mechanism which comprises an upper crank 12 and a lower crank 13. Shafts 14 and 15 of these two cranks are connected together for rotation by the toothed wheels 16 and 17 located at the ends of the shafts 14 and 15.

A crankpin 18 of the crank 12 is connected by a connecting rod 19 to a shaft 20 located on the upper part of the bearing block 7 and a crankpin 21 of the lower crank 13 is connected by a connecting rod 22 to a shaft 23 located on the lower part of the bearing block 7.

The mounting of the mobile mechanism is effected in such a way that the crankpins 18 and 21 of the cranks 12 and 13 are always arranged symmetrically in relation to the midplane of the two shafts 14 and 15 ofthe cranks.

In accordance with the invention counterweights 24 are fastened on the cranks 12 and 13 opposite the crankpins l8 and 21.

The masses of these counterweights 24 may be chosen (taking into account the weights of the other parts of the cranks 12 and 13) in order that, when there is a rotary movement of the cranks, the forces due to the accelerations to which these weights are subjected virtually counterbalance the forces to which the bearing block 7 and the parts which it supports are subjected.

It should be noted that the movements of the cranks 12 and 13 and of the connecting rods 19 and 20 are constantly symmetrical in relation to the midplane of the shafts 14 and 15 of the cranks, in such a manner that the whole mobile mechanism does not exert at any time forces having a resultant perpendicular to the midplane in question (if, naturally, it is not a case of weight forces). However, it is clear that the shafts 14 and 15, do exert on their bearings forces which tend periodically to separate them and to bring them together, but these forces are only communicated to the frame which connects the shafts 14 and 15 of the cranks.

Since in other respects the bearing block 7 is not subjected to any acceleration involving vertical components, it can be seen that it is possible, in accordance with the invention, to bring about a static and dynamic counterbalancing of the mobile parts of the rolling mill.

Indeed, it is possible, by suitably choosing the size of the counterweight 24, to arrange it so that the acceleration forces of the different parts are virtually cancelled out due to the fact that, the mobile counterbalancing device only exerts horizontal forces.

In the above-described embodiment, the connecting rods 19 and 22 are also used for transmitting the oscillating motion to the bearing block 7 by means of a motor (not shown) which drives a shaft 25 on which pinions 26 mesh with the wheels 17.

FIG. 4 shows a variation of FIG. 3, in which the shafts l4 and 15 of the cranks are vertical instead of horizontal.

This embodiment of FIG. 4 may, in certain cases, have the advantage of making the rolled tube leaving the rolls more accessible. The space in which the connecting rods 19 and 22 move can be shielded so that they do not constitute a danger to operators supervising the rolling mill.

In alternative embodiments, which are not shown in the drawing, the driving ofthe eccentric masses can be effected by means of a hydraulic motor, the rotor of which is directly connected with the shafts of the cranks. Preferably, two hydraulic motors with the same features are used, one being coupled to the shaft 14 of the crank 12 and the other to the shaft 15 ofthe crank 13, and this is possible with either the embodiment of FIG. 3 or that of FIG. 4.

In yet a further embodiment, four hydraulic motors with the same features can be used. In this event the motors are located at each end of the shafts 14 and 15 of the cranks 12 and 13.

By virtue of using, according to the invention, hydraulic motors having low speeds of rotation, it is possible, due to the high power to weight ratio of these motors, to considerably reduce the moment of inertia of the masses coupled for rotation with the crankshafts l4 and 15.

In this way the mechanical disadvantages which arise when uniformly rotating masses are rigidly coupled with other masses which undergo periodic accelerations in the course of their rotation are substantially eliminated.

The counterbalancing device used according to the invention makes it possible to provide rolling mills which can function without difficulty at high speed, for example at more than 200 strokes per minute.

In addition, this counterbalancing device allows considerable rolling runs which enables the provision of a sufficient period of tine for ensuring the movements of the blank between the rolling passes, whilst still increasing production.

It will be understood that the above-described embodiments can be modified without departing from the scope of the present invention.

In particular, it will be apparent that the two parts of the mobile mechanism which turn in opposite directions may be arranged differently. For example it is possible to place on the same shaft two counterweights turning in opposite directions. It would also be possible to effect the drive of the bearing block 7 without using the counterbalancing device.

Finally, it will be understood that the counterbalancing device which has been described can equally well be used on rolling mills for nontubular products. Moreover, it can also be used on other machines in which there are similar counterbalancing problems.

What I claim is:

l. A rolling mill comprising a bearing block mounting a pair of rolls, means for reciprocating said bearing block, said means comprising a drive means for producing rotary motion, transmission means for converting said rotary motion to reciprocating motion connecting said drive means to said bearing block, said transmission means comprising two crankshafts driven in opposite directions by said drive means, each crankshaft carrying an eccentric mass and being connected to a connecting rod, said connecting rod being in turn pivotally connected to said bearing block, whereby said bearing block and rolls are counterbalanced during their reciprocating motion.

2. Rolling mill as claimed in claim 1 in which each crankshaft is fixed to a toothed wheel, with the teeth of said wheels engaging each other to synchronize the movements of the two cranks.

3. Rolling mill as claimed in claim 1 in which said crankshafts are horizontal.

4. Rolling mill as claimed in claim 1 in which crankshafts are vertical.

5. Rolling mill as claimed in claim 1 comprising a hydraulic motor connected to drive said eccentric masses.

6. Rolling mill as claimed in claim I in which each crankshaft, is driven by a hydraulic motor, the rotor of which is directly coupled thereto.

7. Rolling mill as claimed in claim 1 in which each crankshaft is driven by two hydraulic motors, the drive members of which are directly coupled thereto. 

1. A rolling mill comprising a bearing block mounting a pair of rolls, means for reciprocating said bearing block, said means comprising a drive means for producing rotary motion, transmission means for converting said rotary motion to reciprocating motion connecting said drive means to said bearing block, said transmission means comprising two crankshafts driven in opposite directions by said drive means, each crankshaft carrying an eccentric mass and being connected to a connecting rod, said connecting rod being in turn pivotally connected to said bearing block, whereby said bearing block and rolls are counterbalanced during their reciprocating motion.
 2. Rolling mill as claimed in claim 1 in which each crankshaft is fixed to a toothed wheel, with the teeth of said wheels engaging each other to synchronize the movements of the two cranks.
 3. Rolling mill as claimed in claim 1 in which said crankshafts are horizontal.
 4. Rolling mill as claimed in claim 1 in which crankshafts are vertical.
 5. Rolling mill as claimed in claim 1 comprising a hydraulic motor connected to drive said eccentric masses.
 6. Rolling mill as claimed in claim 1 in which each crankshaft, is driven by a hydraulic motor, the rotor of which is directly coupled thereto.
 7. Rolling mill as claimed in claim 1 in which each crankshaft is driven by two hydraulic motors, the drive members of which are directly coupled thereto. 